As far as I can tell, "Batang" does not come with Windows 10, nor with Word 2013, and it seems Microsoft wants to charge as much as $129 for it. Yeah right!
I'm using Word 2013 and what I found to look best (good enough for me) are simply the BOLD Capital letters of "Times New Roman" (go figure). I'd show you, but I guess I can't use Times New Roman here.
For numbers greater than 4,999 you'll need one or more overbars. There's a few ways to do an overbar, but the one that looks best to me can be done by inserting a symbol. Let's say you want to represent 106,748. Using Times New Roman, BOLD, type capital
"C", go to Insert -> Symbol -> More Symbols (the shortcut to get there is Alt-n-u-m), then for font (Alt-f) choose "(normal text)", then in the lower right of the dialog (Alt-c), choose "Character code: 0305" and at the top right, the Subset should automatically
switch to "Combining Diacritical Marks". If it doesn't, make sure you typed the letter "C" using Times New Roman, but in any case, you need to choose "(normal text)" or some other font that gives you "Combining Diacritical Marks" and a valid symbol at 0305.
Next, back to the lower right corner (Alt-m), make sure it says "from: Unicode (hex)", then finally press the Insert button (Alt-i, left arrow, Enter). Now your "C" should have an overbar. Next type "V" and when you go back to Insert -> Symbol (Alt-n-u), the
last symbol that was used should always appear as the first choice in the upper left of the pull-down, so press Enter (or click the symbol) and your "V" should have its overbar, too. (If not, check all those previous steps again.) Last type "MDCCXLVII" and
your final result should be the Roman numeral for 106,748: C̅V̅MDCCXLVII
I had mixed results simply using the "0305 Alt-x" shortcut. Sometimes I could type the letter immediately followed by the number "0305" (no space) and then Alt-x and it usually inserts the overbar, but sometimes it didn't work correctly. However, going up
to the Insert Symbols dialog and making sure all the options were correct always worked.
Hope that helps.